The Ambassador of the United Kingdom to Japan is the United Kingdom's foremost diplomatic representative in Japan, and is the head of the UK's diplomatic mission there.

The following is a chronological list of British heads of mission (ministers and ambassadors) in Japan from 1859. Before 1905, there were no ambassadors exchanged between the two countries, the highest rank being envoy extraordinary and minister plenipotentiary – a rank just below ambassador. Before 1859, there was no treaty and no diplomatic relations, because Japan was isolated from the world by the Tokugawa shogunate's policy of national isolation called sakoku (literally locked country).